Pressurized Oxy-Combustion DE-FE0025193 Principal Investigator: - - PowerPoint PPT Presentation

DE-FE0025193 Principal Investigator:

Richard Axelbaum

Washington University

• Dept. Energy, Environmental & Chemical Engineering

NETL Kickoff Meeting

• Oct. 23 2015

Integrated Flue Gas Purification and Latent Heat Recovery for Pressurized Oxy-Combustion

Outline

• Technology Background
• Project Objectives
• Technical Approach
• Project Management

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Technology Background

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• The requirement of high pressure CO2 for sequestration

enables pressurized combustion as a tool to increase efficiency and reduce costs.

• Benefits of Pressurized Combustion

– Recover latent heat in flue gas  improved efficiency & cost – Latent heat recovery can be combine  reduced cost with integrated pollution removal – Reduce gas volume  reduced equipment size – Avoid air-ingress  reduced CO2 purification costs – Fuel flexibility  reduced oxygen requiremen – Controlled radiation heat transfer

Pressurized Oxy-Combustion

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• a. Cost and performance baseline for fossil energy plants volume 1: bituminous coal and

natural gas to electricity. DOE/NETL-2010/1397, rev. 2

• b. Advancing Oxycombustion Technology for Bituminous Coal Power Plants: An R&D
• Guide. DOE/NETL - 2010/1405

a b

ASPEN Plus Results – Plant Efficiency

Gopan A, et al. Applied Energy, 125, 179-188 (2014)

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Coal Feeders Coal Milling Coal ASU Cold Box

O2 Compressor Main Air Compressor

Moist N2

BFW

N2 O2 Air Dry N2 to Cooling Tower

Air Steam Cycle BFW BFW BFW BFW Bottom Ash Bottom Ash Bottom Ash Bottom Ash Steam Cycle Steam Cycle Steam Cycle Steam Cycle BFW Fly Ash Direct Contact Cooler Sulfur Scrubber BFW Steam Cycle

pH Control

Cooling Water Cooling Tower CO2 Boost Compressor

CO2 Purification Unit

Vent Gas CO2 Pipeline Compressor

CO2 to Pipeline

Particulate Filter Steam Cycle

• Std. ASU: O2 P = 1.1 bar

Direct Contact Column SOx and NOx removal

SPOC Process Flow Diagram

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DCC

wash column

cooling water (cw) cw + condensate

Pressure (bar) Exit Temp (C) 16 167 30 192 36 199

flue gas wet flue gas

Latent Heat Recovery – DCC

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SOx and NOx Removal Mechanism

NO NO2 N2O4 N2O3 SO2 HSO3 HNO2 H2SO4 HNO3 Gas Phase Liquid Phase

Questions

• What is the optimum design for the DCC for pressurized oxy-

combustion?

• What is the expected removal efficiency at the proposed
• perating conditions for SPOC?
• What are the optimal DCC operating & inlet conditions?
• Inlet NOx/SOx ratio
• pH
• Temperature
• What are the critical and rate limiting reactions?
• Is one column sufficient?

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Project Objectives

Mission: to develop an enabling technology for simultaneous recovery of latent heat and removal of SOx and NOx from flue gas during pressurized oxy-coal combustion, so as to eliminate conventional FGD and de-NOx processes and minimize the COE.

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Objectives:

• Develop a predictive model for reactor design & operation.
• Experimentally determine critical reactions and rates.
• Conduct parametric study to optimize process.
• Design, build, test prototype for 100 kW pressurized combustor.
• Estimate capital and operating costs of the DCC for a full-scale

SPOC plant.

Technical Approach

Continuously stirred tank reactor - CSTR (bench-scale)

Experiment Modeling

Prototype DCC (100 kW) Kinetic model & reduced mechanism development

Scale

DCC model w/ chemistry & transport SPOC process & econ. model (550 MWe)

kinetic data results design

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Technical Approach: Mechanism and Kinetics

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Knowledge Gaps and Challenges: Reaction Mechanism & Kinetic Model

1. The earlier understanding of the chemistry (the so-called lead chamber process) has been shown to be insufficient but this chemistry is still often used to describe the process. 2. New chemical mechanisms have been proposed but these have been based on existing kinetic data developed under conditions different from this system. 3. A “rational” kinetic model is needed where

• the level of complexity of the model is just sufficient to

characterize the chemistry, and

• the kinetic parameters in the mechanism are obtain by

experiment.

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Building blocks of the Mechanism

1. N (nitrogen) -block

• Gas-phase oxidation of NO into nitrogen oxides

NO2, N2O3 and N2O4

• Liquid-phase dissolution of nitrogen oxides;

production of nitrous and nitric acids (HNO2, HNO3) 2. S (sulfur) -block

• Liquid-phase dissolution of SO2

3. S&N -block

• Liquid-phase interaction between S- and N-

compounds.

• Production of the sulfuric acid (H2SO4)

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Development of the Mechanism

Mechanism reduction: Based on the 33-step mechanism of Norman, et al.,

• Intern. J. of Greenhouse Gas Control, V. 12, January 2013, pp.26-34.,
• A 10-step reduced mechanism has been constructed by

Yablonsky and Temkin.

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NOx Reactions

Gas Phase 1. 2NO (g) + O2(g) 2NO2 (g) 2. 2NO2(g) ↔N2O4(g) 3. NO(g) + NO2(g) →N2O3(g) Gas + Liquid Phase 4. 2 NO2 (g) + H2O (g, aq) HNO2 (aq) + HNO3 (aq) 5. N2O4(g)+ H2O (g, aq) HNO2 (aq) + HNO3 (aq) 6. N2O3(g) + 2H2O (g, aq) 2 HNO2 (aq) 7. 3 HNO2 (aq) HNO3 (aq)+ 2 NO (g, aq)+ H2O (g, aq)

SOx Reactions

8. SO2 (g) + H2O (g, aq) = HSO3

• (aq) + H+ (aq)

SOx + NOx Reactions

9. HNO2 (aq) + HSO3

• (aq) + H+ (aq) → H2SO4 (aq)+ ½ N2O (g) + ½ H2O (aq)

10. 2 HNO2 (aq) + HSO3

• (aq) + H+ (aq) → 2NO (g) + H2SO4 (aq) + H2O (aq)

Rational Mechanism

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Kinetic Modeling: Goals

• 1. Justify or eliminate (add) steps in the mechanism

based on gas- and liquid-phase experimental data conducted in the domain of the anticipated

• perational conditions.
• 2. Estimate contributions of the different routes and

accurately determine reaction parameters for the key reactions.

• 3. Obtain estimates of optimal parameters (initial

composition and pH, temperature and residence times).

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Technical Approach: CSTR Experiments

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Knowledge Gaps and Challenges: SOx and NOx Chemistry

1. Mechanisms and kinetic parameters of consumption/generation of different NOx- and SO2-species in the gas phase and their dissolution in water are well understood.

• Kinetic mechanism for the NO- and SO- containing species in the liquid phase

remains unclear, and some of the kinetic parameters are highly uncertain.

2. Literature regarding influence of pH on capture effectiveness is limited and sometimes contradictory. Because the pH changes as the reaction occurs, it is difficult to predict which mechanism is dominant.

• To date, experimental systems have not controlled or directly measured the

experimental pH values.

3. Difficult to experimentally measure the concentrations of certain key intermediate species.

• Lack of experimental data on the concentrations of critical species makes it

challenging to obtain accurate kinetic data for key chemical reactions in such high pressure, high temperature systems.

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• 1. Gas inlet/liquid outlet with filter; 2. High pressure/temperature pH electrodes;
• 3. Gas outlet and pressure gauge; and 4. Mechanical stirrer

In situ pH measurements and control under high pressure/temperature conditions The reactor design is optimized for conducting experiments under high pressure and temperature and highly acidic conditions

Gas Cylinder Gas Cylinder Gas Cylinder

Gas Cylinder

CO2, O2, SO2, NO, NO2, and N2

Gas Mixer

Temperature Controller

Gas analyzers High pressure charging pump

In situ aqueous species analysis under high pressure and temperature

High Pressure Pump 1 4 2 3

Novel bench-scale experiment setup to obtain kinetic data

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Variables Conditions Pressure (bar) 5, 10, 15, 30 pH 0.5, 1, 2, 3, 4, 5 Temperature (oC) 25, 75, 125, 175, 225, 275, 325 NOx/SO2 ratio 0, 0.1, 0.2, 0.4, 0.8, ∞ SO2 concentration 0.09 – 0.9% O2 gas concentration 0 – 3%

Experimental variables to be used in bench scale studies

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Expected Outcomes of Model Development

• New kinetic data on the absorption and conversion reactions
• f NO, NO2, and SO2 under high temperature and pressure

conditions with controlled pH.

• This will be the first study to conduct experiments under well-

characterized in situ pH conditions.

• An experimentally validated chemical mechanism
• A simplified but reliable kinetic model with experimentally-
• btained kinetic parameters.
• Recommendations on the optimal working regime, i.e.,

reactant concentrations, temperature and pH.

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Prototype DCC Design & Testing

• Packed-bed column

design

• Pressure up to 15 bar
• Coupled to 100kW

pressurized combustion facility

• Test with both

simulated and real flue gas

• Model using

software, e.g. ASPEN and KG Tower

gas analysis (SO2, NOx)

prototype DCC

packing

spray cooling water liquid recirc gas outlet condensate

flue gas pH meas. 23

Figure adapted from: M. J. Jafari, et al., Iranian J. Environ. Healt. 9(1) (2012) 20.

Milestones

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ID Budget Period Task No. Milestone Description Planned Completion Verification Method a 1 2.1 Purchase Bench-Scale Equip. 03/31/2016 Quarterly Report b 1 3.1 Schematic Prototype Column Design 03/31/2016 Quarterly Report c 1 2.2 Preliminary Bench-Scale Tests Complete 06/30/2016 Quarterly Report d 1 3.2 Construct Prototype 09/30/2016 Quarterly Report e 1 4.1 Performance Test w/ Simulated Flue Gas 03/31/2017 Quarterly Report f 1 5.2 Complete Improved Model 06/30/2017 Quarterly Report g 1 4.2 Performance Test w/ Real Flue Gas 09/30/2017 Final Report h 1 6 Full-Scale Cost & Performance Estimate 09/30/2017 Final Report

Project Organization

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Project Management

Richard Axelbaum Ben Kumfer

Modeling

Gregory Yablonsky Oleg Temkin PhD student

Prototype DCC

Ben Kumfer PhD student

Chemical Mechanisms and Kinetics Experiment

Young-Shin Jun PhD student

Process Modeling

Richard Axelbaum Postdoc

Acknowledgements

U.S. Department of Energy:

Award #s DE-FE0025193, DE-FE0009702

Consortium for Clean Coal Utilization:

Sponsors: Arch Coal, Peabody Energy, Ameren

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U.S. DOE Disclaimer

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of the authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.